An inkjet printing system typically includes one or more printheads and their corresponding ink supplies. Each printhead includes an ink inlet that is connected to its ink supply and an array of drop ejectors, each ejector consisting of an ink pressurization chamber, an ejecting actuator and a nozzle through which droplets of ink are ejected. The ejecting actuator may be one of various types, including a heater that vaporizes some of the ink in the pressurization chamber in order to propel a droplet out of the orifice, or a piezoelectric device which changes the wall geometry of the chamber in order to generate a pressure wave that ejects a droplet. The droplets are typically directed toward paper or other recording medium in order to produce an image according to image data that is converted into electronic firing pulses for the drop ejectors as the recording medium is moved relative to the printhead.
A common type of printer architecture is the carriage printer, where the printhead nozzle array is somewhat smaller than the extent of the region of interest for printing on the recording medium and the printhead is mounted on a carriage. In a carriage printer, the recording medium is advanced a given distance along a media advance direction and then stopped. While the recording medium is stopped, the printhead carriage is moved in a direction that is substantially perpendicular to the media advance direction as the drops are ejected from the nozzles. After the carriage has printed a swath of the image while traversing the recording medium, the recording medium is advanced; the carriage direction of motion is reversed, and the image is formed swath by swath.
The ink supply on a carriage printer can be mounted on the carriage or off the carriage. For the case of ink supplies being mounted on the carriage, the ink tank can be permanently integrated with the printhead as a print cartridge so that the printhead needs to be replaced when the ink is depleted, or the ink tank can be detachably mounted to the printhead so that only the ink tank itself needs to be replaced when the ink tank is depleted. Carriage mounted ink tanks typically contain only enough ink for up to about several hundred prints. This is because the total mass of the carriage needs be limited so that accelerations of the carriage at each end of the travel do not result in large forces that can shake the printer back and forth. As a result, users of carriage printers need to replace carriage-mounted ink tanks periodically depending on their printing usage, typically several times per year. Consequently, the task of replacing a detachably mounted ink tank must be simple and must consistently achieve a proper engagement of the ink tank with the printhead. Otherwise, improper mounting of the ink tank may lead to leaks, may cause poorly formed images due to an improper communication of ink from the ink tank to the printhead, and may result in user frustration.
US Patent Application Publication 2008/0151032, incorporated herein by reference, discloses an ink tank having a data storage device mounted on a pedestal such that the pedestal can extend through an opening in a supporting structure of the printhead. As such, when the printhead is mounted on the carriage, and the ink tank is installed in the printhead, the data storage device on the ink tank pedestal makes contact with an electrical contact on the carriage. As a result, the printer can detect that an ink tank has been installed. However, on some occasions, it is found that the user accidentally does not fully press the ink tank into its latched position onto the printhead, but the data storage device still touches the electrical contact on the carriage. Thus, the printer falsely detects a properly installed ink tank when, in fact, the ink tank is improperly installed.
What is needed is a user-friendly mounting configuration that eliminates false indications of ink tank installations while enabling reliable detection of properly mounted ink tanks.